I use a couple 20# co2 bottles with an extra 10# bottle to use during refills. the 20#s are cheaper to refill per #, and take for ever to run out but they are kind of tall, in my 150g setup it barely fits in my xtall stand otherwise the bottles will not fit under your tank so they may have to be out in the open.
The top of the shut out knob on a 20# is about 27' high and I have read not to run the tanks laying on their sides even though I have seen it done.
dan

Mine is the 20 lb one and it is rather tall, I think I am going to have to have it in back of the stand just not inside which means the stand willbe a little farther from the wall.. what you all think about that?

Also is it OK to add CO2 into a tank with fish in it already?
And I know I've asked this before but can you tell me how much more this will improve plant growth and other with adding CO2 to the tank and not just leaving the lighting, the only reason I'm kind of skeptical as this will be a lot of cash out of my pocket and want to make sure it worth it

Absolutely. Just start slow and increase in small amounts waiting 24 hours hours between adjustments. The only danger is overdosing CO2 beyond 30-40ppm...you avoid this by adding CO2 in small amounts to start... say about 1 bubble every 2-3 seconds (20-30 bubbles per minute).

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And I know I've asked this before but can you tell me how much more this will improve plant growth and other with adding CO2 to the tank and not just leaving the lighting, the only reason I'm kind of skeptical as this will be a lot of cash out of my pocket and want to make sure it worth it

No only does it speed growth but more importantly is creates an aids tremendously in creating an environment that favors plant health and growth thereby giving the advantage to plants over algae. Contrasting that would be an environment very low in CO2 so that plants are CO2 limited...then the advantage favors algae. While it's certainly very possible to have planted tanks without CO2 injection and maintain them for long period without CO2 injection, it is a "style and type" of tank that needs to be of lower lighting and specifically planned with non-CO2 injection in mind.

Thanks Steve youve been a big help, I may have a regulator already on the tank will check when I get home, and can't wait to see those pictures from you either... Thanks !!!

You say its OK to insert CO2 into a tank with fish already in there but it drops the pH a lot correct so how would I go about this... I know you said incresing the bubbles little by little starting with about 1 bubble every 2-3 seconds but how many bubbles should I finish up with?

Also would it be easier since I only have 3 fish in the 55 gallon setup just to take them out of the tank for about 3 days and get the CO2 in there and everything and get the pH right and then add the fish?

And I'm sorry you said the PMM when done you said it should be 3 ???

Also when I went to aquabotanic
-- http://www.aquabotanic.com/abstore/en-us/dept_3.html
I looked at the complete CO2 Sytems and they had two things I don't recall you or anyone else mentioning I should get and am wondering if you can tell me what they do and if they are neccessary...
They are solenoid and pH controller (Is pH controller the stuff that comes with a Master Test kit for testing pH)

My question now is for the CO2 Reactor, cause if I'm thinking correctly the reactor distributes the CO2 into the tank as a gas bubble correct?

The CO2 Reactor takes the small bubbles from the needle valve and uses increased contact surface and time to fully dissolve the "bubbles" of CO2. A good reactor will give you close to 100% of the CO2 being dissolved.

Picking a reactor depends largely on whether you want an external reactor or whether you are willing to deal with trying to hide an internal reactor. Another factor is how the reactor is driven. If you have a canister filter you can use it to drive a certain type reactor, otherwise a pump or powerhead will be needed to drive the reactor. While I prefer to DIY build my own reactors I haven't heard any poor reports on the reactors found in your links.

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And then that is everything I need right?

Other than some CO2 resistant or silicon tubing you'd be ready to go.

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And the Bubble Counter on the Millawukee All in One is it a good one and that will tell me how many bubbles are being put into the tank correct?

Yes, that regulator is a very good one used by hundreds of hobbyists. The bubble counter will give you a visual idea of how much CO2 is going into the tank it does not tell you how much CO2 is dissolved into the tank water though. This is the critical issue...knowing exactly (sort of) what the concentration of CO2 is in the water. To determine CO2 concentration you must do an accurate pH and KH test. Those two measurements will allow you to determine the amount of dissolve CO2 in your tank. Note that when CO2 reaches the ideal range of 20-30 ppm your pH will have dropped 0.6 to 1.0. Chuck Gadd has an excellent description on his website along with CO2 charts and calculators needed to determine CO2 levels from your pH and KH test results.